1. Field of the Invention
The present invention relates to a carbapenem compound which has excellent antimicrobial activity and wide range of anti-microbial spectrum, and can be administered not only as an injection but also orally. More particularly, the present invention relates to a novel carbapenem derivative which has a substituted or unsubstituted imidazo[5,1-b]thiazole group or a substituted or unsubstituted imidazo[5,1-b]thiazolium group at the 2-position on the carbapenem ring, or a salt thereof.
2. Background Art
Carbapenem derivatives, by virtue of potent antibacterial activity against a wide spectrum of bacteria, have been energetically studied as a highly useful .beta.-lactam agent, and Imipenem, Panipenem, and Meropenem have been clinically used.
Both Imipenem and Panipenem, however, are used as a mixture due to instability against renal dehydropeptidase-1 ("DHP-1") in the case of Impenem and in order to reduce nephrotoxicity in the case of Panipenem. Meropenem which has recently been marketed has a methyl group at the 1.beta.-position, so that it has increased stability to DHP-1 and thus can be used alone.
However, a need still exists for a drug having higher stability to DHP-1. Furthermore, drugs effective for methicillin resistant Staphylococcus aureus ("MRSA"), penicillin resistant Streptococcus pneumoneae ("PRSP"), resistant Pseudomonas aeruginosa and enterococci which have recently become serious problems as well as influenza have been demanded as well.
Some of the present inventors have previously reported the carbapenem derivatives having a novel heteroaromatic ring imidazo[5,1-b]thiazolium-6-ylmethyl group at the 2-position on the carbapeneni ring in WO 96/028455 and the carbapenem derivatives having an imidazo[5,1-b]thiazole group through a pyrrolidinylthio group at the 2-position of the carbapenem ring in PCT/JP 97/04270.
Further, WO 96/034868 and Japanese Patent Laid-Open Publication No. 273876/1992 disclose the carbapenem derivatives in which a carbon atom on the heteroaromatic ring is bonded to the 2-position of the carbapenem ring. However, there have been described no specific data on the anti-microbial activities or effectiveness for these derivatives. There have been described neither bicyclic heteroaromatic rings nor carbapenem rings having imidazo[5,1-b]thiazole group.